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Pig Dissection
Post-Lab Questions
1. The systems of the pig are very similar to humans, this is how we can use pig organs to
replace or repair our own human organs. What is an explanation for this?
Both of us are vertebrates, both mammals, both placental mammals—many similarities
2. Although similar, pigs have differences in their anatomy from humans. What is the
difference between the pig lungs and the human lungs? Use a diagram to show this
difference. What is the functional unit of the lung? How does gas exchange take place at
the membrane of this functional unit? (use your textbook to support your answer).
PIG: Right Lung 4 lobes (cranial or apical, middle or cardiac, accessory or intermediate, and
caudal or diaphragmatic), Left Lung 2 lobes (cardiac or cranial, and diaphragmatic or caudal)
HUMAN: Right Lung 3 lobes (superior, middle, and inferior), Left Lung 2 lobes (superior and
inferior)
Alveolus is functional unit. Gas exchange takes place across the membrane via partial
pressure changes and diffusion. As inspiration occurs, pressure decreases due to the
movement of the diaphragm, air is drawn into the lung. At the alveolus, O2 levels are lower
inside the bloodstream, so O2 diffuses from alveolus into blood. The opposite is true of CO2.
3. How does fetal circulation differ from adult circulation? Please use a diagram to help
explain your answer. Include in your answer where the source of oxygen is for a fetus,
compared to an adult.
FETAL: RA to RV to Pulmonary Trunk to Ductus Arteriosus to Aorta to Body to Umbilical
Artery to Placenta to Umbilical Vein to Ductus Venosus to Vena Cavae to RA
ADULT: RA to RV to Pulmonary Artery to Lungs to Pulmonary Veins to LA to LV to Aorta to
Body to Vena Cavae
Source of Oxygen for fetus is placenta, adults it is lungs.
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Pig Dissection
4. What are the major differences you noticed in the digestive tract of the pig, compared to
the human tract? This can be explained by what type of animal the pig is, compared to
humans. What type of animal is the pig? Use this information to help you explain the
differences in the digestive tract. (See pp. 42-44).
Spiral colon like ungulates with sectioned stomach—primitive ruminants. Pig also has
cecum, taenia (saculated colon with muscles on one side).
Ruminants have 3 chambered stomach, pigs have only 2 chambers but 4 regions
(esophageal, cardiac gland, region of proper gastric glands, and pyloric)
Pigs have some characteristics of a monogastric (1 chamber in stomach) herbivore as well as
some characteristics of a ruminant.
5. Read the section: Histology of the Kidney on pp. 65-66 of the manual. The kidney of the pig
functions in the same way as the kidney of the human. What are the functional units of the
kidney (of which there are almost 1 million in humans)? How does one functional unit
perform all of the functions of the kidney? Explain these functions. Use a diagram to show
where in the functional unit of the kidney these take place.
Nephron is the functional unit of kidney. The Bowman’s capsule surrounds the glomerulus
which is located in the renal cortex. The glomerulus is connected to a proximal convoluted
tubule and the loop of Henle then leads to a distal convoluted tubule and finally the
collecting duct. The collecting duct emties into the ureter. The collecting duct and loop of
henle dip into the renal medulla.
Nephron functions to maintain homeostasis. 3 major functions. First, filtration (glomerulus
is more permeable to ions such as Na+, Cl-, HCO3-, and H2O. Filtration is hydrostaticpressure driven. Second, Tubular Reabsorption, from fluid in proximal tubule back to blood
(water, glucose, electrolytes, amino acids, creatine, lactic acid, citric acid, uric acid, ascorbic
acid, phosphates, sulfates, calcium, potassium, sodium and water. Third, Tubular Secretion,
from blood into renal tubule (H+, toxins like drugs (penicillin, histamines) ammonia, extra
salts. This ends as urine which consists of ions and water, urea, and uric acid.
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Pig Dissection
6. In the female reproductive systems of the frog, the pig, and the human, there are distinct
differences. One of these differences is apparent in the way substances exit the body of the
female. The frog has one final chamber the cloaca, the pig has a vestibule in the urogenital
papilla, the human has neither of these. Describe these differences and how they show
change over time. Which system is more efficient, why?
FROG: single exit area for all substances
PIG: some differentiation, feces has own pathway, colon-anus, but urine and reproductive
fluid share a pathway (ureters to vestibule to exit), reproductive fluid vagina to vestibule to
exit.
HUMAN: 3 separate tubes keeping all 3 substances separate (urethra v. vagina v. anus)—
most efficient, less chance for contamination, more likely for sperm to fertilize egg.
7. Based on the anatomy of the pig, how would you expect the brainstem to be oriented?
Explain.
Longitudinally—in a horizontal plane rather than vertically due to pigs being quadrupeds
but humans being bipedal.